Structural racks comprising structural members, such as columns and beams, are used widely in warehouses and elsewhere. Commonly, such members are bolted to each other, although it is known to weld such members to each other. Bolted racks are preferred over welded racks, in many cases, because bolted racks can be nondestructively disassembled and the horizontal shelf heights can be changed to suit different load heights.
In making such a rack, it is desirable to employ structural members of standard shapes, such as standard channels, wherever possible Because of their shapes, however, it is difficult to bolt standard channels rigidly to each other at column-to-beam connections in such a rack.
One method to bolt structural members to each other at column-to-beam connections in a structural rack is disclosed in Konstant U.S. Pat. No. 4,678,091. Such patent discloses a bolt having a hexagonal head and extending through respective overlapping but offset apertures in the respective members, so that the bolt provides what is described as "lever action" against the apertures as a hexagonal nut is tightened onto the bolt.
Although the method described in the preceding paragraph may be generally effective, it is necessary to use two wrenches, namely one wrench to hold the nut and another to turn the bolt head. Because the nut is close to a flange of the structural member used as a column, it is difficult to apply a wrench to hold the nut. Moreover, dimensional tolerances needed for the overlapping but offset apertures are difficult to achieve.
Other methods to connect structural members to each other in a structural rack are disclosed in Vincens U.S. Pat. No. 3,398,981, D'Altrui U.S. Pat. No. 3,554,477, McConnell U.S. Pat. No. 4,078,664, and Harmes et al. U.S. Pat. No. 4,291,812.
There has remained a need, to which this invention is addressed, for a better way to bolt structural members, such as standard channels, to each other in a structural rack, as at a column-to-beam connection.